It is known per se to operate high-pressure discharge lamps using electronic ballasts, which have converters having one or a plurality of switching transistors. Full-bridge converters are common. During continuous operation of the lamp, these converters generate DC voltage supply powers for the lamp which, in simple terms, alternate at a low frequency in terms of their polarity. In this case, disruptive phenomena occurring in the event of real and thus asymmetrical DC operation are prevented in the lamp, and, at the same time, disruptive higher frequencies are likewise kept largely remote from the lamp.
It is necessary, in particular, to filter out or to limit remaining so-called ripple current components in the supply power for the lamp using filter capacitors. Reference is made below in this context to a filter capacitor, although variants using a plurality of filter capacitors may also be intended.
When high-pressure discharge lamps are started, a starting voltage of a considerable level must be made available, for example in a range from 1.5 kV to 5 kV (simple amplitude). The started lamp requires a so-called transfer voltage for a certain transition time, and this transfer voltage is greater than the required voltage of the continuous-operation supply power.